Japanese police say they are beginning to make progress in the fight against the trafficking of women into Japan - most of whom are forced into the sex industry. Police are vowing to do more, at a time when Japan is coming under scrutiny from a U.N. investigator looking into human trafficking.

Japan's National Police Agency says a record-high 51 women were trafficked into the country in the first half of this year. The report was issued two days after authorities began enforcing tougher laws that, for the first time, identify human trafficking as a crime, and set punishment for violators.

But the U.N. special investigator on trafficking says the problem in Japan is far worse than official statistics show - with thousands of women, mostly from other Asian states, being brought into the country every year and forced to work in the sex industry.

U.N. Special Rapporteur Sigma Huda, a lawyer from Bangladesh, met with officials at the National Police Agency one day before they released their semi-annual report.

She told reporters after the meeting that a lot of questions she raised about the scope of the problem and actions by police to crack down on traffickers had not been answered.

Completing an unofficial visit to Japan, she vowed to return next year as part of an official inquiry, and said she will want to see if the Japanese government and police are sincere in stepping up their vigilance. "I would want to watch it very carefully," she said. "I would like to see whether there is a reduction - a remarkable reduction - and, secondly, whether there is collusion."

She said it is not only the "receiving states," like Japan, but also the "sending states" that are responsible for the exploitation of women.

Police and private organizations agree that in Japan, women from the Philippines and Thailand are the most common victims. But during the first half of the year, criminal cases also involved victims from such countries as Australia, Estonia, Indonesia, Romania, and South Korea.

Japanese activists say authorities here only got serious about the problem after the State Department put Japan on a special watch list of nations considered at risk of falling into the worst category of offenders. Washington last month removed Japan from the list after revisions were made to the country's penal code.

Ms. Huda blames Japanese cultural attitudes for what she termed a tolerant attitude that makes the exploitation of women possible. She cited the geisha tradition and the country's inability to confront the legacy of so-called "comfort women," those in conquered countries who were forced to provide sexual services to Japanese troops during World War II.